A major item of cooking equipment used and maintained at pizzerias comprises an air impingement tunnel oven having a belt type continuous loop food conveying cooking grate or rack. A common length of baking time for pizzas cooked within such ovens is five minutes. Accordingly, the conveyor motor speed of such an oven is commonly adjusted so that the oven's continuous loop grate longitudinally travels within five minutes a distance equal to the longitudinal length of the oven. Such longitudinal transit time allows a pizza carried into the oven by the conveyor to emerge therefrom and cease cooking at the end of the desired five minutes cooking time.
Many pizzerias cook and serve additional menu items such as oven toasted sandwiches which require a cooking time which is shorter than that of pizzas. A typical oven cooking time for a toasted sandwich is three minutes. Accordingly, where a pizzeria utilizes a conveyor tunnel oven of the type described above to toast a sandwich, the conveyor's motor speed is commonly upwardly adjusted to provide a three minute longitudinal transit time through the oven. A problem associated with such upward adjustment of the conveyor speed arises when a next successive item to be cooked within the oven comprises a pizza which must be cooked at a slower speed. Where a pizza is to be cooked within such a conveyor tunnel oven immediately following a sandwich, a substantially complete transit of the sandwich through the oven must be awaited prior to resetting of the oven for pizza cooking. The process of adjusting and readjusting a single conveyor's speed in accordance with cooking times needed by various food items results in time loss and wastage of the production capacity of the oven.
In order to solve or ameliorate the oven capacity wastage problem discussed above, air impingement food conveying tunnel ovens are known to incorporate dual or side by side conveyors for the provision of simultaneous varying passage times through the oven. However, in such an assembly, dual drive shafts, dual belt driving motors and dual electronic speed controllers are also typically provided. Provision of such additional mechanisms and equipment undesirably results in excess mechanical complexity and excess equipment expense.
The instant inventive air impingement conveyor tunnel oven solves or ameliorates the problems noted above by providing a dual conveyor air impingement tunnel oven which facilitates simultaneous dual transit speeds through the oven with little or no increase in mechanical complexity, and with little or no increase in the cost of equipment or components installed upon the oven. Such mechanical and economic advantages are achieved through the provision of an annularly coffered or radially stepped drive roller, such roller allowing a single drive motor and electronic speed controller to drive dual or side by side conveyors at varying speeds.